1. Technical Field
The present invention relates generally to an apparatus and method for generating a secret key using a change in a wireless channel on a wireless communication network and, more particularly, to an apparatus and method for generating a secret key using a change in a wireless channel on a wireless communication network, which change the phase and amplification gain of a wireless channel regardless of the rate of change in the wireless channel, transmit and receive signals, and generate a secret key based on a received signal.
2. Description of the Related Art
Recently, many encryption techniques have been applied to and used in wireless communication systems. These encryption techniques are problematic in that they have been configured to make computation difficult rather than making the acquisition of a key mathematically impossible, in order to prevent infiltration. Once the computational ability of an infiltrator has increased, the effect of this method is reduced. Accordingly, there is a need fir technology that cons lets an encryption technique that provides an absolute rather than technology that is based on the assumption of computational difficulty.
Furthermore, a centralized secret key distribution method chiefly used in encryption technology is not suitable for an Ad-hoc or peer-to-peer network, that is, a new wireless communication environment. In other words, it is impossible to apply the centralized secret key distribution method to a wireless communication environment because the wireless communication environment is not centrally controlled. Therefore, a new key generation method is required to replace the centralized secret key distribution method.
Meanwhile, in a wireless communication network, correlated random sources that provide an absolute secret can be obtained from the information about a wireless channel. In particular, if a wireless communication system uses a Time Division Duplex (TDD) method two users A and B who have set up a communication link between themselves can each obtain information about the same wireless channel within a specific time. In contrast, an infiltrator who has not set up a wireless link with the users A and B monitors the status of a wireless channel which rarely has a correlation with the wireless channel of the two users.
The two users may generate secret keys using information about the wireless channel which is monitored at a specific time interval by applying this difference to the generation of the secret keys. This key generation method is advantageous in that the center does not need to distribute or generate a key because an entity that performs communication generates a secret key by itself.
The method of generating a secret key using a wireless channel has been proposed as a method by which users who perform wireless communication generate secret keys based on a channel impulse response which is naturally generated in a communication link. These methods are problematic in that they deteriorate the randomness of a secret key and reduce the key generation speed because the status of a wireless channel does not change rapidly when a user is not moving.